<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>1_引出生命周期</title>
</head>
<body>
<!-- 准备好一个"容器" -->
<div id="test1"></div>

<!-- 引入React核心库 -->
<script type="text/javascript" src="../js/react.development.js"></script>
<!-- 引入react-dom，用于支持react操作DOM -->
<script type="text/javascript" src="../js/react-dom.development.js"></script>
<!-- 引入babel，用于将jsx转为js -->
<script type="text/javascript" src="../js/babel.min.js"></script>
<!-- 引入prop-types，用于对组件标签属性进行限制 -->
<script type="text/javascript" src="../js/prop-types.js"></script>

<script type="text/babel">
  // 1.创建组件
  // 生命周期回调函数 <=> 生命周期钩子函数 <=> 生命周期函数 <=> 生命周期钩子
  class Life extends React.Component {

    state = {opacity: 1}

    death = () => {
      ReactDOM.unmountComponentAtNode(document.getElementById('test1'))
    }

    // 组件挂载完毕
    componentDidMount() {
      this.timer = setInterval(() => {
        // 获取原状态
        let {opacity} = this.state
        // 减少0.1
        opacity -= 0.1
        if (opacity <= 0) {
          opacity = 1
        }
        // 设置新的透明度
        this.setState({opacity})
      }, 200)
    }

    // 组件将要卸载
    componentWillUnmount() {
      clearInterval(this.timer)
    }

    // 初始化渲染、状态更新之后
    render() {
      return (
        <div>
          <h2 style={{opacity: this.state.opacity}}>React学不会怎么办？</h2>
          <button onClick={this.death}>不活了</button>
        </div>
      )
    }
  }

  // 2.渲染组件到页面
  ReactDOM.render(<Life />, document.getElementById('test1'))
</script>
</body>
</html>
